Use-and-clobber insns and REG_DEAD notes (fwd)

[Richard Henderson]

On Tue, Jul 15, 2003 at 01:13:05AM +0200, Ulrich Weigand wrote:
> As part of this patch you have removed a comment:
> !      [snip] Which begs the whole
> !      question of whether we should in fact have death notes for registers
> !      used and clobbered (but not set) in the same insn.  [snip]
> 
> This is exactly the question I have here ;-)  Does the fact that
> you removed the comment imply that you had answered the question?

I think that the death note SHOULD exist in the clobber case.

> Is there a way for combine to call back into flow to ask whether
> a dead note is required?

Well, there's a way to get combine to call back into flow when it
gets too confused, yes (see refresh_blocks) but that's usually used
for when we've changed global life.  I'd expect us to be able to 
get this right inside combine.


r~